1. Field of the Invention
The present invention relates to a novel bisphosphite compound and a method for producing aldehydes by subjecting an olefinic compound to a hydroformylation reaction in the presence of a catalyst containing such a phosphite compound and a Group VIII metal.
2. Discussion of Background
The reaction which comprises reacting an olefinic compound with carbon monoxide and hydrogen in the presence of a catalyst in a solvent to produce aldehydes or alcohols as their hydrogenated products, is well-known as hydroformylation reaction. As the catalyst, it is common to use a soluble complex of a Group VIII metal having an organic phosphorus compound as a ligand. The ligand used together with the metal component of the catalyst gives substantial influence to the catalytic reaction. Also in the hydroformylation reaction, it is widely known that the catalytic activity and the selectively are substantially influenced by the ligand. In order to carry out the hydroformylation reaction industrially advantageously, it is important to improve the catalytic activity and the selectivity of the product. Accordingly, various efforts to design the ligand have been made for this purpose.
Various phosphite compounds are known as a group of phosphorus compounds which may be used as the ligands. In addition to monophosphites such as trialkylphosphites or triarylphosphites, various phosphite compounds including polyphosphites having plural coordinating phosphorus atoms in their molecules, have been proposed. For example, Japanese Unexamined Patent Publications No. 116587/1987 and No. 116535/1987 disclose bisphosphite compounds containing two phosphorus atoms in their molecules. Further, Japanese Unexamined Patent Publication No. 178779/1993 discloses bisphosphite compounds having a .beta.-naphthyl group or a phenyl group substituted at a specific position.
As mentioned above, various phosphite compounds have been proposed as the ligand to be used for the hydroformylation reaction. However, the selectivity of the desired product formed in the hydroformylation reaction using these compounds have not necessarily been satisfied, and the formation of by-products has brought about an economical disadvantage to commercial production. Among such by-products, paraffins formed by reduction of an olefinic compound with hydrogen without a hydroformylation reaction, are particularly valueless, since they are not useful other than as fuels. Accordingly, it has been desired to develop a phosphite ligand which does not cause such a reduction reaction as a side-reaction.